Skyline, Ltd., '77. To Front Royal, March 26 and April 2; to Charlottesville, March 27 and April 3. $18.50 adults, $15 children 5 to 11. 534-1100.

The windows actually open on the steam excursion trains the National Railway Historical Society runs to Front Royal and Charlottesville. You can lean out and wave and take pictures. What is more, the excursions always include a photo run-by for photographers, movie-makers and tape recorders. That means you can disembark into a field and stand behind rope lines, recording history as the train backs up out of sight, then comes rushing on with full steam and bells clanging, for a good view of the shining black 70-year-old engine.

Along the way, guides tell the history of the railway line during the Civil War and point out the highlights of the route. Once you arrive at Front Royal or Charlottesville, you can walk around to see the town (in Charlottesville, take a shuttle bus into town) or picnic or buy lunch. These Skyline, Ltd. trips begin at 8 a.m. in Alexandria's Union Station, and return at 6:30 or 7:30 p.m. Last year's trips were popular enough to have carried ten thousand people. There must be something to it.